Commonly, toy safes employ combination locks, which are unlocked by manipulation in accordance with combinations of two, three, or more alphanumeric characters, usually two or three numbers or two or three letters. Lockable containers of other types, such as liquor cabinets, may employ such locks.
Problems can arise with a lockable container employing a combination lock, particularly with a toy safe employing such a lock, if the combination of alphanumeric characters needed for unlocking the lock is lost, misplaced, or forgotten. It would cause such a lock to be largely useless if the needed combination were displayed where such combination could be easily viewed by a casual observer.
However, it would be very useful if the needed combination could be displayed where it could be viewed by an informed observer, but not by an uninformed observer. If the lockable container would be a toy safe used by a young child, the informed observer could be a parent, a babysitter, or an older sibling.